Battery electric vehicles, extended-range electric vehicles, and hybrid electric vehicles all use a rechargeable high-voltage battery as a source of electrical power. One or more high-voltage electric motors alternately draw power from and deliver power to the battery during vehicle operation. When the vehicle is propelled solely using electricity from the battery, the powertrain operating mode is typically referred to as an electric-only (EV) mode. Depending on the vehicle design, additional operating modes may include fixed gear modes and electrically variable transmission (EVT) modes in which an internal combustion engine is used to generate at least some of the torque needed for propelling the vehicle.
Within a hybrid vehicle control architecture, a speed encoder measures the rotational speed of a traction motor in the form of a digital pulse train. However, due to certain physical anomalies the encoder signal does not represent the true rotational speed of the traction motor. Instead, a variation pattern repeats itself with each revolution of the motor. This variation pattern is referred to as angular wobble, and it may have characteristics that contain multiple harmonics of the base revolution period.